Location of the Fracture Faces Within the Cell Envelope of Acinetobacter Species Strain MJT/F5/5

The cell wall of the gram-negative bacterium Acinetobacter species strain MJT/F5/5 shows in thin section an external “additional” layer, an outer membrane, an intermediate layer, and a dense layer. Negatively stained preparations showed that the additional layer is composed of hexagonally arranged subunits. In glycerol-treated preparations, freeze-etching revealed that the cell walls consist of four layers, with the main plane of fracture between layers cw 2 and cw 3. The surface of [Formula: see text] 2 consisted of densely packed particles, whereas [Formula: see text] 3 appeared to be fibrillar. In cell envelopes treated with lysozyme by various methods, the removal of the dense layer has detached the outer membrane and additional layer from the underlying layers, as shown in thin sections. When freeze-etched in the absence of glycerol, these detached outer membranes with additional layers fractured to reveal both the faces [Formula: see text] 2 and [Formula: see text] 3 with their characteristic surface structures, and, in addition, both the external and internal etched surfaces were revealed. This experiment provided conclusive evidence that the main fracture plane in the cell wall lies within the interior of the outer membrane. This and other evidence showed that the corresponding layers in thin sections and freeze-etched preparations are: the additional layer, cw 1; the outer membrane, cw (2 + 3); and the intermediate and dense layers together from cw 4. Because of similarities in structure between this Acinetobacter and other gram-negative bacteria, it seemed probable that the interior of the outer membrane is the plane most liable to fracture in the cell walls of most gram-negative bacteria.     

Fracture Faces in the Cell Envelope of Escherichia coli

Freeze-fracturing of Escherichia coli cells in the presence of 30% (v/v) glycerol resulted in a double cleavage of the cell envelope exposing two convex and two concave fracture faces ([Formula: see text], [Formula: see text] and [Formula: see text], [Formula: see text]) with characteristic patterns. Complementary replicas revealed the relationship of the fracture faces to their corresponding fracture planes. The inner fracture plane splits the plasma membrane at one particular level. Apparently the outer fracture plane was located in the outer part of the wall, as it was separated by a layer ([Formula: see text]) from the fractured profile (CW1) presumably corresponding to the murein layer. The outer fracture plane did alternate toward the cell periphery, exposing complementary smooth areas ([Formula: see text] and [Formula: see text]). When cells were freeze-fractured in the absence of glycerol, the outer cell surface appeared as an etching face rather than a fracture face. A schematic representation of the relative location of the different fracture faces in the E. coli cell envelope is given.     

Ocean acidification leads to counterproductive intestinal base loss in the gulf toadfish (opsanus Beta)

Abstract Oceanic CO(2) has increased from 280 to 380 μatm since preindustrial times and is expected to reach 1,900 μatm by 2300. In addition, regional upwelling zones exhibit levels up to 2,300 μatm, making exploration at future global projected CO(2) levels ecologically relevant today. Recent work has demonstrated that CO(2) exposure as low as 1,000 μatm induces acidosis in toadfish (Opansus beta), leading to metabolic compensation by retention of blood [Formula: see text] in an effort to defend pH. Since increased serosal [Formula: see text] translates to increased [Formula: see text] secretion rates in isolated intestinal tissue, we predicted that blood elevation of [Formula: see text] and Pco(2) during exposure to 1,900 μatm CO(2) would increase in vivo base secretion rates. Rectal fluid and CaCO(3) excretions were collected from toadfish exposed to 380 (control) and 1,900 μatm CO(2) for 72 h. Fluids were analyzed for pH, osmolality, ionic composition, and total CO(2). Precipitated CaCO(3) was analyzed for titratable alkalinity, Mg(2+), and Ca(2+) content. Fish exposed to 1,900 μatm CO(2) exhibited higher rectal base excretion rates, higher rectal fluid [Formula: see text] (mmol L(-1)), and lower fluid Cl(-) (mmol L(-1)) than controls, suggesting increased intestinal anion exchange as a result of the compensated respiratory acidosis. This study verifies that imminent projected CO(2) levels expected by the year 2300 lead to greater intestinal [Formula: see text] loss, a process that acts against compensation for a CO(2)-induced acidosis.     

Copper(I)-alkyl sulfide and -cysteine tri-nuclear clusters as models for metallo proteins: a structural density functional analysis

After having set up the computational methodology for Cu(I)-sulfur systems as models for copper proteins, namely using the simple ligands H(2)S, HS(-), CH(3)SH, and CH(3)S(-), the Cu(I)-Cysteine systems have been investigated: [Cu(I)( S -H(2)Cys) (n) ](+) (H(2)Cys, cysteine, NH(2),SH,COOH) [Cu(I)( S -HCys) (n) ](1-) (n) (NH(2),S(-),COOH). Finally, the structures for bi-nuclear [Formula: see text] (Et, CH(2)CH(3)), [Formula: see text] and tri-nuclear [Cu(I)( S -SH)](3), [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] (NH(2),SH,COOH), [Formula: see text] (NH(2),S(-),COOH, and NH(2),SH,COO(-)), as well as [Formula: see text] (NH(2),S(-),COO(-)), were also optimized to mimic the active center for a metallo-chaperone copper transport protein (CopZ). The X-ray structures for the biomolecules were matched fairly well as regards the Cu-S bond distances and Cu…Cu contact distances in the case the model cysteine S atom is deprotonated. Upon protonation of ligand S atoms, the conformation of clusters is altered and might bring about the di- and tri-nuclear core breakage. These findings suggest that subtle protonation/deprotonation steps, i.e. small and/or local pH changes play a significant role for copper transport processes.     

Unifying Time to Contact Estimation and Collision Avoidance across Species

The [Formula: see text]-function and the [Formula: see text]-function are phenomenological models that are widely used in the context of timing interceptive actions and collision avoidance, respectively. Both models were previously considered to be unrelated to each other: [Formula: see text] is a decreasing function that provides an estimation of time-to-contact (ttc) in the early phase of an object approach; in contrast, [Formula: see text] has a maximum before ttc. Furthermore, it is not clear how both functions could be implemented at the neuronal level in a biophysically plausible fashion. Here we propose a new framework - the corrected modified Tau function - capable of predicting both [Formula: see text]-type ("[Formula: see text]") and [Formula: see text]-type ("[Formula: see text]") responses. The outstanding property of our new framework is its resilience to noise. We show that [Formula: see text] can be derived from a firing rate equation, and, as [Formula: see text], serves to describe the response curves of collision sensitive neurons. Furthermore, we show that [Formula: see text] predicts the psychophysical performance of subjects determining ttc. Our new framework is thus validated successfully against published and novel experimental data. Within the framework, links between [Formula: see text]-type and [Formula: see text]-type neurons are established. Therefore, it could possibly serve as a model for explaining the co-occurrence of such neurons in the brain.     

Mapping of redox state of mitochondrial cytochromes in live cardiomyocytes using Raman microspectroscopy

This paper presents a nonivasive approach to study redox state of reduced cytochromes [Formula: see text], [Formula: see text] and [Formula: see text] of complexes II and III in mitochondria of live cardiomyocytes by means of Raman microspectroscopy. For the first time with the proposed approach we perform studies of rod- and round-shaped cardiomyocytes, representing different morphological and functional states. Raman mapping and cluster analysis reveal that these cardiomyocytes differ in the amounts of reduced cytochromes [Formula: see text], [Formula: see text] and [Formula: see text]. The rod-shaped cardiomyocytes possess uneven distribution of reduced cytochromes [Formula: see text], [Formula: see text] and [Formula: see text] in cell center and periphery. Moreover, by means of Raman spectroscopy we demonstrated the decrease in the relative amounts of reduced cytochromes [Formula: see text], [Formula: see text] and [Formula: see text] in the rod-shaped cardiomyocytes caused by H(2)O(2)-induced oxidative stress before any visible changes. Results of Raman mapping and time-dependent study of reduced cytochromes of complexes II and III and cytochrome [Formula: see text] in cardiomyocytes are in a good agreement with our fluorescence indicator studies and other published data.     

Morphology and Viscoelasticity of Actin Networks Formed with the Mutually Interacting Crosslinkers: Palladin and Alpha-actinin

Actin filaments and associated actin binding proteins play an essential role in governing the mechanical properties of eukaryotic cells. Even though cells have multiple actin binding proteins (ABPs) that exist simultaneously to maintain the structural and mechanical integrity of the cellular cytoskeleton, how these proteins work together to determine the properties of actin networks is not clearly understood. The ABP, palladin, is essential for the maintenance of cell morphology and the regulation of cell movement. Palladin coexists with [Formula: see text]-actinin in stress fibers and focal adhesions and binds to both actin and [Formula: see text]-actinin. To obtain insight into how mutually interacting actin crosslinking proteins modulate the properties of actin networks, we characterized the micro-structure and mechanics of actin networks crosslinked with palladin and [Formula: see text]-actinin. We first showed that palladin crosslinks actin filaments into bundled networks which are viscoelastic in nature. Our studies also showed that composite networks of [Formula: see text]-actinin/palladin/actin behave very similar to pure palladin or pure [Formula: see text]-actinin networks. However, we found evidence that palladin and [Formula: see text]-actinin synergistically modify network viscoelasticity. To our knowledge, this is the first quantitative characterization of the physical properties of actin networks crosslinked with two mutually interacting crosslinkers.     

Limits to the rate of adaptive substitution in sexual populations

In large populations, many beneficial mutations may be simultaneously available and may compete with one another, slowing adaptation. By finding the probability of fixation of a favorable allele in a simple model of a haploid sexual population, we find limits to the rate of adaptive substitution, [Formula: see text], that depend on simple parameter combinations. When variance in fitness is low and linkage is loose, the baseline rate of substitution is [Formula: see text], where [Formula: see text] is the population size, [Formula: see text] is the rate of beneficial mutations per genome, and [Formula: see text] is their mean selective advantage. Heritable variance [Formula: see text] in log fitness due to unlinked loci reduces [Formula: see text] by [Formula: see text] under polygamy and [Formula: see text] under monogamy. With a linear genetic map of length [Formula: see text] Morgans, interference is yet stronger. We use a scaling argument to show that the density of adaptive substitutions depends on [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] only through the baseline density: [Formula: see text]. Under the approximation that the interference due to different sweeps adds up, we show that [Formula: see text], implying that interference prevents the rate of adaptive substitution from exceeding one per centimorgan per 200 generations. Simulations and numerical calculations confirm the scaling argument and confirm the additive approximation for [Formula: see text]; for higher [Formula: see text], the rate of adaptation grows above [Formula: see text], but only very slowly. We also consider the effect of sweeps on neutral diversity and show that, while even occasional sweeps can greatly reduce neutral diversity, this effect saturates as sweeps become more common-diversity can be maintained even in populations experiencing very strong interference. Our results indicate that for some organisms the rate of adaptive substitution may be primarily recombination-limited, depending only weakly on the mutation supply and the strength of selection.     

Application of DFT methods to the study of the coordination environment of the VO2+ ion in V?proteins

Density functional theory (DFT) methods were used to simulate the environment of vanadium in several V proteins, such as vanadyl-substituted carboxypeptidase (sites A and B), vanadyl-substituted chloroplast F(1)-ATPase (CF(1); site 3), the reduced inactive form of vanadium bromoperoxidase (VBrPO; low- and high-pH sites), and vanadyl-substituted imidazole glycerol phosphate dehydratase (IGPD; sites α, β, and γ). Structural, electron paramagnetic resonance, and electron spin echo envelope modulation parameters were calculated and compared with the experimental values. All the simulations were performed in water within the framework of the polarizable continuum model. The angular dependence of [Formula: see text] and [Formula: see text] on the dihedral angle θ between the V=O and N-C bonds and on the angle φ between the V=O and V-N bonds, where N is the coordinated aromatic nitrogen atom, was also found. From the results it emerges that it is possible to model the active site of a vanadium protein through DFT methods and determine its structure through the comparison between the calculated and experimental spectroscopic parameters. The calculations confirm that the donor sets of sites B and A of vanadyl-substituted carboxypeptidase are [[Formula: see text], H(2)O, H(2)O, H(2)O] and [N(His)(||), N(His)(⊥), [Formula: see text], H(2)O], and that the donor set of site 3 of CF(1)-ATPase is [[Formula: see text], OH(Thr), H(2)O, H(2)O, [Formula: see text]]. For VBrPO, the coordination modes [N(His)(||), N(His)(∠), OH(Ser), H(2)O, H(2)O(ax)] for the low-pH site and [N(His)(||), N(His)(∠), OH(Ser), OH(-), H(2)O(ax)] or [N(His)(||), N(His)(∠), [Formula: see text], H(2)O] for the high-pH site, with an imidazole ring of histidine strongly displaced from the equatorial plane, can be proposed. Finally, for sites α, β, and γ of IGPD, the subsequent deprotonation of one, two, and three imidazole rings of histidine and the participation of a carboxylate group of a glutamate residue ([N(His)(||), [Formula: see text], H(2)O, H(2)O], [N(His)(||), N(His)(||), [Formula: see text], H(2)O], and [N(His)(||), N(His)(||), [Formula: see text], OH(-), [Formula: see text]], respectively) seems to be the most plausible hypothesis.     

Specificity of Hpa II and Hae III DNA methylases

The methylases M.HaeIII and M.HpaII recognize the tetranucleotide sequences [Formula: see text] and [Formula: see text] respectively, in DNA, and transfer a methyl group from S-adenosylmethionine to the 5-position of cytosine on each strand as indicated by the asterisks. Restriction endonuclease R.HaeIII does not cleave the methylated sequence [Formula: see text] but can cleave [Formula: see text] in which methylation is introduced on the unnatural external cytosine positions. Similarly, R.HpaII does not cleave [Formula: see text] but can cleave [Formula: see text].Images     

A Mathematical Model of Rift Valley Fever with Human Host

Rift Valley Fever is a vector-borne disease mainly transmitted by mosquito. To gain some quantitative insights into its dynamics, a deterministic model with mosquito, livestock, and human host is formulated as a system of nonlinear ordinary differential equations and analyzed. The disease threshold [Formula: see text] is computed and used to investigate the local stability of the equilibria. A sensitivity analysis is performed and the most sensitive model parameters to the measure of initial disease transmission [Formula: see text] and the endemic equilibrium are determined. Both [Formula: see text] and the disease prevalence in mosquitoes are more sensitive to the natural mosquito death rate, d(m). The disease prevalence in livestock and humans are more sensitive to livestock and human recruitment rates, [Formula: see text] and [Formula: see text], respectively, suggesting isolation of livestock from humans is a viable preventive strategy during an outbreak. Numerical simulations support the analytical results in further exploring theoretically the long-term dynamics of the disease at the population level.     

Critical motor number for fractional steps of cytoskeletal filaments in gliding assays

In gliding assays, filaments are pulled by molecular motors that are immobilized on a solid surface. By varying the motor density on the surface, one can control the number [Formula: see text] of motors that pull simultaneously on a single filament. Here, such gliding assays are studied theoretically using Brownian (or Langevin) dynamics simulations and taking the local force balance between motors and filaments as well as the force-dependent velocity of the motors into account. We focus on the filament stepping dynamics and investigate how single motor properties such as stalk elasticity and step size determine the presence or absence of fractional steps of the filaments. We show that each gliding assay can be characterized by a critical motor number, [Formula: see text]. Because of thermal fluctuations, fractional filament steps are only detectable as long as [Formula: see text]. The corresponding fractional filament step size is [Formula: see text] where [Formula: see text] is the step size of a single motor. We first apply our computational approach to microtubules pulled by kinesin-1 motors. For elastic motor stalks that behave as linear springs with a zero rest length, the critical motor number is found to be [Formula: see text], and the corresponding distributions of the filament step sizes are in good agreement with the available experimental data. In general, the critical motor number [Formula: see text] depends on the elastic stalk properties and is reduced to [Formula: see text] for linear springs with a nonzero rest length. Furthermore, [Formula: see text] is shown to depend quadratically on the motor step size [Formula: see text]. Therefore, gliding assays consisting of actin filaments and myosin-V are predicted to exhibit fractional filament steps up to motor number [Formula: see text]. Finally, we show that fractional filament steps are also detectable for a fixed average motor number [Formula: see text] as determined by the surface density (or coverage) of the motors on the substrate surface.     

(13)C NMR Reveals No Evidence of n-π* Interactions in Proteins

An [Formula: see text] interaction between neighboring carbonyl groups has been postulated to stabilize protein structures. Such an interaction would affect the [Formula: see text]C chemical shielding of the carbonyl groups, whose paramagnetic component is dominated by [Formula: see text] and [Formula: see text] excitations. Model compound calculations indicate that both the interaction energetics and the chemical shielding of the carbonyl group are instead dominated by a classical dipole-dipole interaction. A set of high-resolution protein structures with associated carbonyl [Formula: see text]C chemical shift assignments verifies this correlation and provides no evidence for an inter-carbonyl [Formula: see text] interaction.     

Robustness and information propagation in attractors of random boolean networks

Attractors represent the long-term behaviors of Random Boolean Networks. We study how the amount of information propagated between the nodes when on an attractor, as quantified by the average pairwise mutual information ([Formula: see text]), relates to the robustness of the attractor to perturbations ([Formula: see text]). We find that the dynamical regime of the network affects the relationship between [Formula: see text] and [Formula: see text]. In the ordered and chaotic regimes, [Formula: see text] is anti-correlated with [Formula: see text], implying that attractors that are highly robust to perturbations have necessarily limited information propagation. Between order and chaos (for so-called "critical" networks) these quantities are uncorrelated. Finite size effects cause this behavior to be visible for a range of networks, from having a sensitivity of 1 to the point where [Formula: see text] is maximized. In this region, the two quantities are weakly correlated and attractors can be almost arbitrarily robust to perturbations without restricting the propagation of information in the network.     

The biosynthesis of 4-hydroxycoumarin and dicoumarol by Aspergillus fumigatus Fresenius

A strain of Aspergillus fumigatus Fresenius, isolated from spoiled hay, converts melilotic acid (o-hydroxyphenylpropionic acid) and o-coumaric acid into 4-hydroxycoumarin and dicoumarol. The sequence is shown to be melilotic acid (I) [Formula: see text] coumaric acid (IV) [Formula: see text] beta-hydroxymelilotic acid (II) [Formula: see text] beta-oxomelilotic acid (III) [Formula: see text] 4-hydroxycoumarin (VI), on the basis of (1) studies on the formation of postulated intermediates, (2) experiments with isotopically labelled materials and (3) sequential enzyme induction. In the presence of semicarbazide, o-coumaraldehyde is formed from o-coumaric acid: there is no evidence, however, that this lies on the normal metabolic pathway.     

Stochastic simulations of pattern formation in excitable media

We present a method for mesoscopic, dynamic Monte Carlo simulations of pattern formation in excitable reaction-diffusion systems. Using a two-level parallelization approach, our simulations cover the whole range of the parameter space, from the noise-dominated low-particle number regime to the quasi-deterministic high-particle number limit. Three qualitatively different case studies are performed that stand exemplary for the wide variety of excitable systems. We present mesoscopic stochastic simulations of the Gray-Scott model, of a simplified model for intracellular Ca[Formula: see text] oscillations and, for the first time, of the Oregonator model. We achieve simulations with up to [Formula: see text] particles. The software and the model files are freely available and researchers can use the models to reproduce our results or adapt and refine them for further exploration.     

On Why Thylakoids Energize ATP Formation Using Either Delocalized or Localized Proton Gradients – A Ca2+ Mediated Role in Thylakoid Stress Responses

By the early 1970s, the chemiosmotic hypothesis of Peter Mitchell was widely accepted by bioenergetics researchers as the best conceptual scheme to explain how ATP is formed in oxidative and photosynthetic phosphorylation. At about the same time, however, work from a few laboratories suggested that some aspects of that elegant, relatively simple hypothesis required revision - not abandonment, but refinement to accommodate more complex movements of protons in the ATP formation mechanism than originally envisioned by Peter Mitchell. In some situations it appeared that protons were constrained to localized domains rather than always delocalized within an enclosed vesicle as envisioned by chemiosmosis. This minireview tells that story from my perspective, as one of the researchers involved in the experimental approaches that revealed more complex energy coupling proton flux patterns. Ionic conditions during isolated thylakoid storage were found to reversibly switch the [Formula: see text] gradient driving ATP formation between delocalized and localized energy coupling modes. Thylakoid accessible Ca(2+) ions proved to be the switching factor that was responding to the ionic conditions in the storage treatment. The mechanism of Ca(2+) was at least partially demystified when it was shown that the reversible switching between [Formula: see text] energy coupling modes involved Ca(2+) interactions with the 8 kDa CF(0) (the H(+) channel) subunit in a type of H(+) flux gating action. Other experiments showed that the Ca(2+) gating of H(+) flux into the lumen may be a critical regulatory factor in controlling the lumen pH and thereby help regulate the activity of the violaxanthin de-epoxidase enzyme, a key part of the chloroplast photoprotective response to over-energization (excess light) stress.     

The IspA protease's involvement in the regulation of the sporulation process of Bacillus thuringiensis is revealed by proteomic analysis

We have observed that the process of sporulation of the ispA-deficient mutant was delayed under phase-contrast microscopy. The protein profiles of the ispA-deficient mutant have been analyzed using two-dimensional gel electrophoresis. The results of a proteomic analysis using MALDI-TOF MS indicated that a sporulation-associated protein, pro- [Formula: see text], was upregulated, while two other sporulation-associated proteins, SpoVD and SpoVR, were downregulated in the ispA-deficient mutant. It has been known that pro- [Formula: see text] is a precursor of [Formula: see text] and is required for gene expression related to the late stage of sporulation. Moreover, SpoVD and SpoVR are known to be involved in the formation of the spore cortex. Based on these observations, we propose that the delay in the sporulation process observed in the ispA-deficient mutant may be due to a failure of [Formula: see text] to signal sporulation. This phenomenon may be further enhanced by insufficient amount of SpoVD and SpoVR for cortex formation. In this study, we have revealed for the first time a possible pathway for the regulation of sporulation-associated proteins via IspA.     

Exploiting magnetic resonance angiography imaging improves model estimation of BOLD signal

The change of BOLD signal relies heavily upon the resting blood volume fraction ([Formula: see text]) associated with regional vasculature. However, existing hemodynamic data assimilation studies pretermit such concern. They simply assign the value in a physiologically plausible range to get over ill-conditioning of the assimilation problem and fail to explore actual [Formula: see text]. Such performance might lead to unreliable model estimation. In this work, we present the first exploration of the influence of [Formula: see text] on fMRI data assimilation, where actual [Formula: see text] within a given cortical area was calibrated by an MR angiography experiment and then was augmented into the assimilation scheme. We have investigated the impact of [Formula: see text] on single-region data assimilation and multi-region data assimilation (dynamic cause modeling, DCM) in a classical flashing checkerboard experiment. Results show that the employment of an assumed [Formula: see text] in fMRI data assimilation is only suitable for fMRI signal reconstruction and activation detection grounded on this signal, and not suitable for estimation of unobserved states and effective connectivity study. We thereby argue that introducing physically realistic [Formula: see text] in the assimilation process may provide more reliable estimation of physiological information, which contributes to a better understanding of the underlying hemodynamic processes. Such an effort is valuable and should be well appreciated.     

The effects of dissolved oxygen levels on the metabolic interaction between digestion and locomotion in Cyprinid fishes with different locomotive and digestive performances

To test whether the effects of water oxygen concentration ([O(2)]) on the metabolic interaction between locomotion and digestion differ between fish species with different locomotive and digestive behaviours in normoxia, we investigated the swimming performance of fasted and fed fish at water [O(2)] of 1, 2 and 8 (normoxia) mg L(-1) (2.5, 5 and 20 kPa) at 25°C in three juvenile Cyprinidae fish species: goldfish (Carassius auratus), common carp (Cyprinus carpio) and qingbo (Spinibarbus sinensis). Digestion, taxon and water [O(2)] all had significant effects on the pre-exercise oxygen consumption rate [Formula: see text] and the swimming performance (P < 0.05). Among the three fishes, qingbo showed the highest swimming performance and the lowest feeding [Formula: see text] at the saturated water [O(2)], and its active oxygen consumption rate [Formula: see text] and critical swimming speed (U (crit)) decreased the most with decreases in water [O(2)]. Qingbo exhibited a locomotion-priority metabolic mode at all three water [O(2)]. Digestion was sacrificed to locomotion in a postprandial swimming situation, but fed qingbo could not maintain their U (crit) at water [O(2)] of 2 and 1 mg L(-1). Goldfish showed the lowest swimming performance and the highest feeding [Formula: see text] at the saturated water [O(2)]. They exhibited a digestion-priority metabolic mode at high water [O(2)]. However, with a decrease in water [O(2)], the feeding [Formula: see text] decreased more acutely than the respiratory capacity; thus, digestion and locomotion performed independently in a postprandial swimming situation (i.e., an additive metabolic mode) at a water [O(2)] of 1 mg L(-1). The common carp showed moderate and balanced swimming performance and feeding [Formula: see text] at the saturated water [O(2)], and exhibited an additive metabolic mode at all 3 water [O(2)], because digestion, swimming and respiratory capacities decreased in parallel with the decrease in water [O(2)].